The role of the Biology Core is to characterize the compounds synthesized by the Chemistry Core (Core B) using GEMS luciferase reporter assays, ELISA, and western blot analysis. The data generated by these assays is reported back to the Chemistry Core to help make decisions regarding the subsequent rounds of chemical synthesis. Analog synthesis and biological screening are performed iteratively, allowing for refinement of the lead molecules described in the Chemistry Core section. This effort is expected to allow for a variety of structures to identify compounds with improved efficacy, selectivity, and physicochemical and pharmacokinetic properties. In addition, the results generated by the Biology Core will be used to determine the compounds that will be characterized by the Pharmacology Core (Core C). Compounds that are active in the biological assays will be evaluated in pharmacological assays and then continue to the Efficacy Assessment Core (Core D) for ex vivo studies using muscles from mdx mice and eventually in vivo studies.